Glutaric acid production by systems metabolic engineering of an l-lysine-overproducing <i>Corynebacterium glutamicum</i>.

Abstract

There is increasing industrial demand for five-carbon platform chemicals, particularly glutaric acid, a widely used building block chemical for the synthesis of polyesters and polyamides. Here we report the development of an efficient glutaric acid microbial producer by systems metabolic engineering of an l-lysine-overproducing <i>Corynebacterium glutamicum</i> BE strain. Based on our previous study, an optimal synthetic metabolic pathway comprising <i>Pseudomonas putida</i> l-lysine monooxygenase (<i>davB</i>) and 5-aminovaleramide amidohydrolase (<i>davA</i>) genes and <i>C. glutamicum</i> 4-aminobutyrate aminotransferase (<i>gabT</i>) and succinate-semialdehyde dehydrogenase (<i>gabD</i>) genes, was introduced into the <i>C. glutamicum</i> BE strain. Through system-wide analyses including genome-scale metabolic simulation, comparative transcriptome analysis, and flux response analysis, 11 target genes to be manipulated were identified and expressed at desired levels to increase the supply of direct precursor l-lysine and reduce precursor loss. A glutaric acid exporter encoded by <i>ynfM</i> was discovered and overexpressed to further enhance glutaric acid production. Fermentation conditions, including oxygen transfer rate, batch-phase glucose level, and nutrient feeding strategy, were optimized for the efficient production of glutaric acid. Fed-batch culture of the final engineered strain produced 105.3 g/L of glutaric acid in 69 h without any byproduct. The strategies of metabolic engineering and fermentation optimization described here will be useful for developing engineered microorganisms for the high-level bio-based production of other chemicals of interest to industry.